It is well known to cover the external walls of a building with horizontal planks, known as “siding.” More recently, similarly shaped panels of aluminum or plastic have been used for the same purpose. Plastic siding panels are typically several feet long and 8 to 12 inches high, and may be molded to imitate the appearance of two or three narrower planks. These panels are typically attached to the substructure of the building by nails driven through slots in the top edge of the panel. The height of the panel is limited to eight or 12 inches by the amount of weight that can satisfactorily be hung from the top edge of the panel. As with traditional siding, the bottom panel is set to a reference line, for example, a snapped chalk line, and each successive panel is mounted overlapping the panel below. This system has the considerable disadvantage that, because the relatively narrow panels must be attached one at a time working up from the bottom of the wall, it is difficult to keep the panels accurately horizontal and parallel. That is especially true when the siding is being installed by a homeowner or other person who is not professionally trained. Also, the process cannot easily be mechanized, because the nails must be left slightly loose, so that the panels can slide from side to side as they expand or contract. That makes the use of power-operated nail guns very difficult.
It has also been proposed to provide clips attached to the substructure to which the siding panels can be attached. That makes attaching the actual panels quicker and easier, but at the expense of requiring great effort to position the clips accurately spaced and in horizontal lines.
U.S. Pat. No. 4,288,958 to Chalmers et al. proposes a siding system with long vertical stringers that have clips preformed at regular intervals. Each clip supports the top of one panel, and retains the bottom of the panel above. In addition, an extra tab is provided midway between adjacent clips, which can be used to stabilize a vinyl panel formed with the appearance of two planks.
However, Chalmers's device has significant limitations. First, because the panel is still supported only at the top, the height of the panel is still limited to 8 to 12 inches. Second, Chalmers's system requires the top of the panel to be partly inserted into the clip above so that the panel is loosely supported. The panel is then pressed against the stringers, and finally slid upwards so that the panel becomes locked into the clip at its top and hooked under the clip at its bottom and, if applicable, the additional tab in the middle. That is a rather awkward maneuver to carry out over the length of a long panel, because the whole length of the panel, both along the middle and along the bottom, must be held close against the stringers at one time. If the panel is being installed above a window frame or the like that projects from the wall, so that the panel cannot slide over the window frame, the upward movement would leave a gap that would need to be covered over, and a standard J-channel could not be used. In addition, Chalmers's siding panels do not appear to be easy to remove. The metal clips would likely bend out of shape, and the vinyl panels interlock with barbs. His vinyl panels also appear difficult to manufacture, because they appear to be a modification of a design originally intended to be made of aluminum sheet.
There is therefore still room for considerable improvement in the design of siding panels and siding panel mounting systems.